This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A282193 #20 Feb 05 2025 22:02:53 %S A282193 1,1,2,4,6,12,36,96,240,480,1440,5760,17280,40320,120960,483840, %T A282193 1935360,5806080,17418240,69672960,348364800,1045094400,3832012800, %U A282193 15328051200,76640256000,229920768000,919683072000,4598415360000,22072393728000,71735279616000,286941118464000,1434705592320000 %N A282193 a(n) is the minimal product of a positive integer sequence of length n with no duplicate substrings (forward or backward) of length greater than 1. %H A282193 Peter Kagey, <a href="/A282193/a282193_1.hs.txt">Haskell program for A282193</a>. %e A282193 a(1) = 1 via [1]; %e A282193 a(2) = 1 via [1,1]; %e A282193 a(3) = 2 via [1,1,2]; %e A282193 a(4) = 4 via [1,1,2,2]; %e A282193 a(5) = 6 via [1,1,2,3,1]; %e A282193 a(6) = 12 via [1,1,2,2,3,1]; %e A282193 a(7) = 36 via [1,1,2,2,3,3,1]; %e A282193 a(8) = 96 via [1,1,2,2,3,1,4,2]; %e A282193 a(9) = 240 via [1,1,2,2,3,1,4,5,1]; %e A282193 a(10) = 480 via [1,1,2,2,3,1,4,2,5,1]; %e A282193 a(11) = 1440 via [1,1,2,2,3,3,1,4,2,5,1]; %e A282193 a(12) = 5760 via [1,1,2,2,3,1,4,2,5,1,6,2]. %e A282193 ... %e A282193 [1,2,3,1,2] is invalid because the substring [1,2] appears twice. %e A282193 [1,2,1] is invalid because the substring [1,2] appears twice (once forward and once backward). %Y A282193 Cf. A282168 is the sum analog. %Y A282193 Cf. A081456, A282164, A282169, A282170. %K A282193 nonn %O A282193 1,3 %A A282193 _Peter Kagey_, Feb 08 2017 %E A282193 Terms a(13) onward from _Max Alekseyev_, Feb 05 2025